In general, semiconductor manufacturing processes for manufacturing semiconductor devices require high precision, and thus, high cleanliness and special production technology have been demanded.
For this reason, semiconductor devices are manufactured in a state in which foreign substances contained in air are completely prevented from contacting the devices, that is, in a vacuum state, and thus, products with high reliability and completeness may be manufactured.
Meanwhile, in order to maintain a vacuum state inside a process chamber for manufacturing semiconductor devices, a vacuum pump for suctioning air and other gases in the process chamber is installed outside the process chamber.
In addition, a vacuum valve is installed between the process chamber and the vacuum pump. When the air and other gases in the process chamber are discharged to the outside, the vacuum valve is opened, and when the vacuum state in the process chamber is maintained, the vacuum valve is closed. Thus, the inside of the process chamber may always be maintained at a clean vacuum state.
Among such vacuum valves, the “mount-type rectangular gate valve” disclosed in patent document 1 (Korean Patent Application Laid-open Publication No. 10-2003-0050409) is a rectangular gate valve including: an air cylinder which vertically moves a shaft while maintaining vacuum using O-rings; a rectangular disk, and a main body provided with a rectangular passage thereon. This valve had merits in that the disk and the passage had a high sealing effect and the disk could be easily manufactured, because the valve was provided with: a rectangular opening/closing disk including four mounting rolls which were hingedly connected to the shaft of the cylinder and respectively provided on four edge portions; side rolling rolls rolling on left and right side surfaces, and a rectangular O-ring having sides around the front surface of the disk, four mounting balls disposed on rear inner surfaces of the rectangular gate valve main body and having a lifting angle corresponding to the mounting rolls; and ball plungers protruding from inside of the front surface of the main body and configured such that three ball plungers were respectively provided to be biased to left and right sides; and the disk, the side rolling rolls, and the ball plungers were configured to apply force always in the direction in which the rectangular opening/closing disk moved away from the front surface of the main body, and configured such that the rectangular opening/closing disk was vertically moved by the vertical movement of the shaft, and as the mounting rolls moved upward along the mounting balls, the rectangular opening/closing disk provided with the O-ring came into close contact with the passage of the front surface and provides perfect sealing.
However, the “mount-type rectangular gate valve disclosed in patent document 1 was provided with, in a subject moving space, the four mounting rolls, side rolling rolls, and the rectangular opening/closing disk provided with the O-ring, and thus had a limitation in that when the rectangular opening/closing disk continuously operates, wear of the mounting rolls, side rolling rolls, and the O-ring occurred and thereby caused air leak and particles generated in the subject moving space.
In addition, there was a limitation in that since, in the above-mentioned structure configured such that when the rectangular opening/closing disk moved upward by an air cylinder, the mounting rolls moved upward riding on tilted mounting balls and the rectangular opening/closing disk closed the passage, the rectangular opening/closing disk was vertically moved by pneumatic pressure generated from an air cylinder without a separate configuration, so that if aid leaks in the air cylinder, the rectangular opening/closing disk was arbitrarily opened and thus could not normally operate.